The demographic transition model
Stage one of the model illustrates high CBR and CDR. This stage depicts an era prior to the Industrial Revolution when families had many children. More children meant more people to work on the family farm. Other factors that contributed to the CBR included no family planning, and faith of the people, which may look at large families as a sign of wealth and fertility.
Stage two as medications, sanitation and technology improved in the mid-1800s, Western European countries seen a decline in death rates. More infants were surviving, and a longer life expectancy was established due to higher living standards and health care. The birth rate however continued to increase due to traditional views of wealth and fertility. As a result, populations grew rapidly
Stage three shows a low CBR and CDR. CDR is already low due to improved technologies and health care. Family planning, better education, lower infant mortality rate, a more industrialized way of life and the want for more material possessions as well as women being able to go out to work, account for the low CBR. Population growth in developed countries is largely due to immigration from less developed countries.
3. The Industrial Revolution is the name given to the movement in which machines changed people's way of life as well as their methods of manufacturing goods. Most products people in the industrialized nations use today are turned out swiftly by the process of mass production, by people working on assembly lines using power-driven machines. People of ancient and medieval times had no such products. They had to spend long, tedious hours of hand labor even on simple objects. The energy, or power, they employed in work came almost wholly from their own and animals' muscles. About the time of the American Revolution, the people of England began to use machines to make cloth and steam engines to run the machines. A little later they invented locomotives. Productivity began a spectacular climb. By 1850 most Englishmen were laboring in industrial towns and Great Britain had become the workshop of the world. From Britain the Industrial Revolution spread gradually throughout Europe and to the United States. Changes That Led to the Revolution
The most important changes that industrial revolution activity brought to the 21st century was the invention of machines to do the work of hand tools; the use of steam, and later of other kinds of power, in place of the muscles of human beings and of animals; and the adoption of the factory system.
5. Population dynamics refers to the branch of life sciences that studies short-term and long-term changes in the size and age composition of populations, and the biological and environmental processes influencing those changes. Population dynamics deals with the way populations are affected by birth rates , death rates, immigration, emigration and studies topics such as ageing populations or population decline.
Birth rate is the ratio of total live births to total population in a specified community or area over a specified period of time. The birthrate is often expressed as the number of live births per 1,000 of the population per year. Death rate also know as mortality rate is a measure of the number of deaths (in general, or due to a specific cause) in a population, scaled to the size of that population, per unit time. Mortality rate is typically expressed in units of deaths per 1000 individuals per year. Immigration is one element it is the movement to a country; emigration is movement from a country. Immigration or emigration on a large scale is often for economic reasons or because of religious, political, or social persecution (which may create refugees), and often results in restrictive legislation by individual countries. The USA has received immigrants on a larger scale than any other country, more than 50 million during its history.
World population continues to increase. With current world population now over 6 billion people, there is significant pressure for excess population to migrate from more densely populated countries to those less populated.